1. Field of the Invention
The present invention relates to medical devices with polymeric coatings and more particularly to medical devices having polymer coatings that release therapeutic agent.
2. Brief Description of the Background Art
Numerous medical devices have been developed for the delivery of therapeutic agents to the body. For example, in accordance with some delivery strategies, a therapeutic agent is provided within a polymeric carrier layer that is associated with a medical device. Once the medical device is placed at the desired location within a patient, the therapeutic agent is released from the medical device. The desired release profile for the therapeutic agent is dependent upon the particular treatment at hand, including the specific condition being treated/prevented, the specific therapeutic agent selected, the specific site of administration, and so forth.
Therapeutic agents are frequently handled in aqueous solutions. Unfortunately, directly coating the surface of a metallic medical device, for example, a stent, with an aqueous solution can be problematic, because metals are typically quite hydrophobic. As a result, the cohesive forces within the aqueous solution tend to pool the solution on the medical device surface, rather than wetting the entire surface. Low coating retention, frequently involving very expensive therapeutic agents, is associated with this phenomenon.